Hydrogen sulfide is frequently encountered in drilling oil and gas wells. It is corrosive to the drill pipe and casing. When a drill pipe breaks due to hydrogen sulfide embrittlement, the drilling operation must be interrupted and the drill pipe string repaired. It is also a pollutant to the environment and a risk to the health and lives of the drilling personnel. Low concentrations of hydrogen sulfide produce irritation of conjunctiva and mucous membranes, headackes, dizziness, nausea, and lassitude. Exposure to high concentrations can result in death.
Magnetite has been used as a weighting material in drilling muds, as shown in U.S. Pat. No. 2,276,075; but without effectively scavenging hydrogen sulfide or substantial improvement in mud rheology.